Python 3.14 Release Notes

Release Date: October 7, 2025

Python 3.14 is a stable release that introduces significant improvements across the language, standard library, and CPython internals.

What's New in Python 3.14

Performance Improvements

• Introduction of a new experimental interpreter design aimed at improving bytecode execution speed.
• Continued CPython optimizations (including GC and internal structures).
• Foundations for future JIT and adaptive optimizations.

Language Enhancements

• PEP 649 / PEP 749: Deferred evaluation of annotations:

  • Annotations are no longer evaluated at definition time.
  • Improves performance and usability.
  • New annotationlib module for working with annotations. :contentReference[oaicite:6]{index=6}

• PEP 750: Template string literals (t-strings):

  • New string type similar to f-strings.
  • Enables custom string processing workflows. :contentReference[oaicite:7]{index=7}

• Improved error messages and diagnostics.

Concurrency and Execution

• PEP 779: Experimental support for free-threaded Python:

  • Optional GIL-less execution mode.
  • Major step toward true parallelism. :contentReference[oaicite:8]{index=8}

• PEP 734: Multiple interpreters in the standard library:

  • Enables isolated concurrent execution. :contentReference[oaicite:9]{index=9}

Standard Library

• New compression.zstd module (PEP 784):

  • Native support for Zstandard compression. :contentReference[oaicite:10]{index=10}

• Improved asyncio introspection.

• Syntax highlighting in the REPL.

• General usability and CLI improvements.

C API and Internals

• Updates to the limited C API for better encapsulation.
• Removal of deprecated APIs and macros.
• Improvements in configuration and build safety.

Runtime Behavior

• Incremental garbage collector.
• Changes in multiprocessing defaults (forkserver on Unix).
• Updated annotation behavior may affect introspection-heavy code. :contentReference[oaicite:11]{index=11}

Migration

Upgrading from Python 3.13 is generally smooth, but consider:

• Changes in annotation behavior.
• Rebuilding binary extensions.
• Avoiding reliance on internal or undocumented APIs.

Official 3.14 Documentation